The specific aims and objectives of this proposed research are to investigate the physical properties and ultrastructure of bacteria by the methods of ultracentrifugation and electron microscopy. It is thought that ultracentrifugation of bacteria will cause a displacement and distortion of their organelles in much the same way as it does in eukaryotic cells, and, if so, further information bearing on the following problems may be obtained: (1) the relationship of the nucleoid ("nucleus") to the cytoplasm; (2) the relation, if any, of the nucleoid and/or "chromosome" to the mesosome and plasma membrane; (3) the nature of the forces which hold the nucleoid body within its "typical", or normal position; (4) the physical behavior of the nucleoid substance when displaced in the cytoplasm; (5) the relative density of the ribosomes and other cytoplasmic granules, and (6) the effects of ultracentrifugation on the viability of the organisms. In addition to the displacement and stratification of the materials within the bacteria, efforts will be made to study the redistribution of these materials, with the view of better understanding the mechanism and physical changes involved in the redistribution process.